The invention relates to energy meters, and particularly energy meters having interchangeable registers.
Energy meters, such as utility power meters, include two basic components: a meter chassis having a transducer which senses energy usage and produces a signal proportional to the energy usage; and a register which converts the signal into a form for accumulation and display. The register must be matched to the transducer so that the readings produced by the register will be an accurate representation of the energy usage sensed by the transducer.
In recent years, meters having interchangeable registers have been developed in order to meet different metering requirements. For examples, different registers can be provided in modular form to provide demand information, time-of-use information and time-of-use/load profile information. In addition, the use of replaceable registers enables a faulty register to be replaced easily without requiring replacement of the entire meter.
The standard transducer used on most residential applications is an electro-mechanical device whose output component is a rotating disk. The disk output is calibrated such that one disk revolution represents a given quantity of energy, which is known as the watt-hour constant, Kh.
The rotating disk may be mechanically coupled, via gears, to a mechanical register which stores the number of revolutions of the disk and provides a visual indication thereof. The gearing between the disk and the register is normally designed to provide a direct readout in units of kilowatt-hours. If the register of such a meter must be replaced, the replacement register must have a gear ratio which corresponds to the Kh value of the meter.
There are also known electronic registers constructed to be coupled to transducers which produce an electrical signal in the form of an output pulse train indicative of energy usage. One transducer of this type includes a disk similar to that used in mechanical transducers but constructed to cooperate with an optical sensor to cause the optical sensor to produce, during each disk revolution, a plurality of pulses which are converted to electrical pulses. The number of pulses produced during each disk revolution, Pr, varies widely from one meter type to another, and is generally in the range of 2-16 pulses per revolution. The quantity of energy usage represented by each pulse constitutes the watt-hour constant of the meter (Kh) divided by the number of pulses per disk revolution (Pr) and is represented by the term ##EQU1## A replacement register for such a meter must be provided with the value of at least K associated with the meter transducer in order for the register to produce meaningful data.
Known electronic register modules include a memory, which may be constituted by a plurality of PROMs, provided to store data identifying the meter to which the register module is to be connected. Conventionally, this data is supplied to the register module by personnel using a computer which can be connected to the register module. This allows a single register module to be used in meters having different transducer constants. However, this procedure must be carried out by properly trained personnel and requires a certain amount of time and care.